ratios for 1297, 155ku, and 13’cs were very close to the hypothetical ratios estimated for thermonuclear fission of 2738u. 8. Estimation of Radioiodine Activity per Unit Area Based on Soil Activity for !29I. From the archival measurements, the iodine isotope activity was estimated per unit area of soil at the cessation of fallout at Rongelap (see Table 8). The enrichment of the iodine isotopes was assumed to be the same as for I. The total radioiodine soil activity per unit area, based on 129 content of archival soils from Rongelap, exceeded the estimated total activity of all radionuclides per unit area by a factor of 10. The estimated total activity was based on four soil samples taken and measured for beta activity on March 8, 1954 (0C68). The radioiodine soil activity per unit area, based on archival soils from Utirik, exceeded the estimated total soil activity per unit area by a factor of 7. Because these archival soil based estimates were so much greater than measured activity, the assumption could not be made that iodine isotopes mimicked the behavior of 297, and thus the usefulness of archival soil measurements was limited. The level of !29r in archival soil may be real, an artifact of the neutron activation technique, or the residue from other weapons tests occurring near the time of soil collection. Comparison of Bikini ash results to hypothetical results for 1297 (Table 7, column D/E) leads one to believe that some enrichment of !291 occurred but not to the extent indicated by our extrapolation of archival soil measurements (Table 7, column B/E). The level of activity of I in Bikini ‘ash was based on direct measurements of !29Te and 1321 (1856). Table 8 Activity of Iodine Isotopes Based on Archival Soil Results Iodine Isotope Activity per Unit Area at Rongelap at 0.5 Day, uci m724 129; 30 1.4x1074 1.9x10? 9.0x1076 9.2x10° 2.0x106 2.0x104 4.9x104 5.2x1076 5.3x106 9.3x104 I 133; 1347 1357 Total 5 8x10 2.5x106 8Multiply by 3.7 x 104 to obtain Bq m2, - 18 - Activity Area at at 1.5 uci per Unit Utirik Days, m7+4 2.5x10 9 .8x103